The present invention relates generally to an improvement in techniques for monitoring an audio signal of a given channel module in an audio signal processing apparatus which includes a plurality of channel modules for performing signal processing on audio signals input thereto and a main output section for outputting the audio signals having been subjected to the signal processing in the channel modules. More particularly, the present invention relates a technique for permitting signal processing for a previewing purpose (i.e., previewing signal processing) separately from main signal processing.
As well known in the art, the audio mixers (hereinafter referred to simply as “mixers”) include a plurality of channel modules each for performing signal processing on an audio signal of one channel, and the audio mixers selectively mixes one or more audio signals and outputs a resultant mixed signal through a main output (terminal). The mixers also include a monitor output separate from the main output such that audio signals of one or more channels can be output from the monitor output. With such a monitor function, a user can listen to, i.e. monitor, audio signals of any desired one or more channels through the monitor output separate from the main output (see, for example, “YAMAHA DIGITAL MIXING CONSOLE PM5D/PM5DRH” published in 2004 by Yamaha Corporation which is available from the Internet at http://www2.yamaha.co.jp/manual/pdf/pa/japan/mixers/PM5DJ1.pdf).
With the conventionally-known monitor function, however, while an audio signal of a given channel module is being output to the main output, the user cannot change a parameter value of the channel module and monitor the changed result, without influencing the audio signal of the main output. For example, during an actual performance in a concert or theater play, the user may want to change a parameter value and confirm a changed result of the parameter value with a view to checking settings of parameters to be used in another performance. However, even in such a case, the conventionally-known monitor function does not allow the user to change a parameter value for a checking purpose as for a channel module that is being used for the main output.
In connection with the aforementioned problem, Japanese Patent Application Laid-open Publication No. 2002-319914 discloses a preview function which displays, on a display device or the like, results obtained by changing values of parameters currently set in one or more channel modules, i.e. changed parameter settings. With this preview function disclosed in the No. 2002-319914 publication, a user can confirm, through the display, changed results of parameter values of channels currently used in the main output, without influencing the main output. With this technique, however, the user can confirm the changed results only visually and cannot listen to audio signals having been processed on the basis of the changed results of the parameter values.
Further, there has been known a connection mode called a mirror mode, where two mixers (i.e., two engines each provided with a DSP unit) are provided and audio signals are coupled to the individual mixers in parallel. In this connection mode (mirror mode), while a processed result in one of the two mixers is output from a main output, the other of the two mixers can perform signal processing independently of the one mixer and output a result of the signal processing from a monitor output (see, for example, Japanese Patent Application Laid-open Publication No. HEI-05-157578). In this case, however, two mixers, i.e. signal processing resources for the two mixers, have to be provided, and thus, particularly in the case of a large-scale mixer having a large number of channels, an enormous quantity of resources would be required.